Method for recovering bitumen from oil sand

ABSTRACT

In one aspect, the present invention provides a method for recovering bitumen from an oil sand, the method comprising: (a) contacting a bitumen-containing oil sand with a first solvent mixture of cyclohexane and ethanol to provide an extraction mixture comprising a sand phase and an organic phase; (b) separating the sand phase from the organic phase comprising bitumen, ethanol and cyclohexane; (c) separating an azeotropic mixture comprising cyclohexane and ethanol from the organic phase; and (d) recovering bitumen from the organic phase. The first solvent mixture comprises from about 95 to about 65 percent cyclohexane and from about 5 to about 35 percent ethanol.

BACKGROUND

The invention relates generally to a method for recovering oil from oilbearing sand, and more particularly to a recovering of such oil in formof bitumen by a method that includes contacting bitumen-containing sandwith a liquid medium.

The world population, especially in the developed and developingindustrial countries, consumes enormous amounts of energy. It isestimated that about half of the amount of energy consumed comes frompetroleum products. As the traditional sources of oil are beingexhausted, and as increased demand supports a relatively high price foroil in the global marketplace, there is a growing need for thedevelopment of alternate sources of oil.

One such alternate source of oil is oil bearing sands such as oil shaleand tar sands. Despite the fact that enormous amounts of oil are presentin the oil shale and tar sand deposits and the fact that such depositsare located in many of the most technologically advanced countries(including the United States and Canada), the amounts of oil actuallyobtained from these deposits are significantly lower than the amount ofoil obtained from traditional oil sources. The reason for this seemingparadox is that oil in the oil shale and tar sands is more difficult andexpensive to recover than oil from a traditional oil source.

A number of processes for the recovery of oil from oil sands have beenexplored over the past few years. These processes include directcombustion (heating or retorting), solvent extraction, water flotationand many variations of these processes to extract oil from the oilsands. Organic material recoverable from oil sands is at times referredto as bitumen. However currently known processes for the extraction ofoil in form of bitumen from oil sands face both technical and economicchallenges. One important technical disadvantage of known processes isthe relatively low recovery rate of bitumen from a treated oil sand. Forexample, in a water flotation process only about 50 to about 70 percentof the bitumen is recovered from the oil sand. It is difficult toseparate and recover bitumen from oil sands because the organic materialcomprising the oil sand is both a complex chemical mixture and may bebound to the inorganic components of the oil sand and/or physicallytrapped within the interstices of the sand component of the oil sand.Thus, a variety of bitumen recovery schemes involve the application ofheat to the oil sand or solvent treatment of the oil sand in order toenhance the recovery of bitumen from the sand.

One known method of recovering useful organic material from oil sands isreferred to as the retorting method, which involves heating the oil sandand recovering a distillate. A serious limitation of the retortingmethod is that it is energy and capital intensive and produces as aby-product a spent sand which may require further treatment before itcan be disposed of appropriately. The energy intensiveness of theprocess can be better appreciated by considering the cost of sustainedheating of large volumes of oil sand at high temperature. Generallytemperatures employed in the retorting process range between about 500°C. and about 800° C. Large capital expenditures are needed for equipmentused to heat the oil bearing sand, even if the heating is carried out insitu. The oil recovered from oil sands by conventional processes, suchas retorting, is not identical in composition to the conventional crudeoil recovered from the ground and for many applications such oil sandoil has to be further treated by distillation, coking of residue and/orhydrogenation to achieve the required characteristics.

Another approach to recovering oil from an oil bearing sand has been toextract the oil with one or more solvents. Thus, extractive separationof bitumen from oil sands using organic solvents such as hydrocarbonsand is known. In addition, extracting oil from oil shale using a varietyof organic solvents at elevated temperatures and at elevated pressureshas also been tried. Known extraction processes have not been entirelysuccessful because they employ organic solvents which are generallyquite expensive relative to the value of the recovered bitumen and mayrequire the use of high temperatures and high pressures. The use of hightemperatures and/or pressures, in turn, necessitates the use ofsophisticated and expensive equipment. The solvent employed may itselfhave a very strong affinity for the sand being treated, and thusrecovery of the solvent employed may present an additional technicalchallenge and economic issue.

There remains a need for the efficient recovery of useful bitumen fromoil sand which is responsive to the economic realities of recovering arelatively low-value organic product from an abundant natural resourceand the ecological imperative of doing so in a manner consistent withthe highest principles of environmental stewardship.

BRIEF DESCRIPTION

In one aspect, the present invention provides a method for recoveringbitumen from an oil sand, the method comprising: (a) contacting abitumen-containing oil sand with a first solvent mixture of cyclohexaneand ethanol to provide an extraction mixture comprising a sand phase andan organic phase; (b) separating the sand phase from the organic phasecomprising bitumen, ethanol and cyclohexane; (c) separating anazeotropic mixture comprising cyclohexane and ethanol from the organicphase; and (d) recovering bitumen from the organic phase. The firstsolvent mixture comprises from about 95 to about 65 percent cyclohexaneand from about 5 to about 35 percent ethanol.

In another aspect, the present invention provides a method forrecovering bitumen from an oil sand, the method comprising: (a)contacting in situ a bitumen-containing oil sand in a subsurface depositwith a first solvent mixture of cyclohexane and ethanol to provide anextraction mixture comprising a sand phase and an organic phase; (b)removing the organic phase comprising bitumen, cyclohexane and ethanolfrom the subsurface deposit; (c) separating an azeotropic mixturecomprising cyclohexane and ethanol from the organic phase; and (d)recovering bitumen from the organic phase. The first solvent mixturecomprising from about 95 to about 65 percent cyclohexane and from about5 to about 35 percent ethanol.

In yet another aspect, the present invention provides a method forrecovering bitumen from an oil sand, the method comprising: (a)contacting at ambient temperature a bitumen-containing oil sand with afirst solvent mixture comprising about 69 cyclohexane and about 31percent ethanol to provide an extraction mixture comprising a sand phaseand an organic phase; (b) separating the sand phase from the organicphase comprising bitumen, ethanol and cyclohexane; (c) separating anazeotropic mixture comprising cyclohexane and ethanol from the organicphase; and (d) recovering bitumen from the organic phase. The firstsolvent mixture being used in an amount corresponding to a weight ratioof first solvent mixture to oil sand in a range from about 3 to 1 toabout 500 to 1.

DETAILED DESCRIPTION

In the following specification and the claims, which follow, referencewill be made to a number of terms, which shall be defined to have thefollowing meanings.

The singular forms “a”, “an” and “the” include plural referents unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

It is also understood that terms such as “top,” “bottom,” “outward,”“inward,” and the like are words of convenience and are not to beconstrued as limiting terms. Furthermore, whenever a particular featureof the invention is said to comprise or consist of at least one of anumber of elements of a group and combinations thereof, it is understoodthat the feature may comprise or consist of any of the elements of thegroup, either individually or in combination with any of the otherelements of that group.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about”, is not to be limited to the precise valuespecified. In some instances, the approximating language may correspondto the precision of an instrument for measuring the value. Similarly,“free” may be used in combination with a term, and may include aninsubstantial number, or trace amounts, while still being consideredfree of the modified term.

As discussed in detail below, embodiments of the present inventioninclude a method for recovering bitumen from an oil sand, the methodcomprising: (a) contacting a bitumen-containing oil sand with a firstsolvent mixture of cyclohexane and ethanol to provide an extractionmixture comprising a sand phase and an organic phase; (b) separating thesand phase from the organic phase comprising bitumen, ethanol andcyclohexane; (c) separating an azeotropic mixture comprising cyclohexaneand ethanol from the organic phase; and (d) recovering bitumen from theorganic phase.

As used herein “oil sands” also includes but not limited to tar sands,extra heavy oils, oily sludge wastes, oil-bearing diatomites, oilshales, tar saturated sandstones and the like. Further, oil sands asused herein also include mined oil sands as well as crude output fromsteam assisted gravity drainage processes (SAG-D processes). The methodsprovided by the present invention may be applied to both mined oil sands(oil sands removed from a first location to a second location fortreatment), and subsurface oil sand deposits. When applied to asubsurface oil sand deposit the method is at times herein referred to asan in-situ recovery method, and for example, the oil sand is said to becontacted in situ with the first solvent mixture to provide anextraction mixture.

Oil sands are a type of bitumen deposit which may be found as depositsnear the surface of the earth or in subsurface deposits. Oil sanddeposits located near the surface of the earth may be mined usingsurface mining techniques and transported from a first location wherethe oil sand is mined to a second location where the oil sand issubjected to treatment for bitumen recovery. In one embodiment, the oilsand is a subsurface deposit not readily accessible using surface miningtechniques.

The oil sands may comprise a mixture of sand, clay, water,organometallic compounds, and a dense and viscous form of petroleum alsoknown as bitumen. Oil sands may also be referred to as “unconventionaloil” or “crude bitumen”. Bitumen is especially prone to the formation ofhighly stable emulsions due to its chemical complexity which varies fromdeposit to deposit, its occurrence in nature with water containing avariety of inorganic species, and the considerable shear forces that thecontents of an oil deposit may experience during capture by a man-madeconduit.

As noted, the present invention provides a method in which abitumen-containing oil sand is contacted with a first solvent mixture.The first solvent mixture includes a mixture of cyclohexane and ethanol.In one embodiment, the first solvent mixture includes cyclohexane andethanol in a ratio from about 95 weight percent to about 65 weightpercent of cyclohexane and from about 5 weight percent to about 35weight percent of ethanol based on the total weight of the first solventmixture. In another embodiment, the first solvent mixture includes amixture of cyclohexane and ethanol in a ratio from about 90 weightpercent to about 65 weight percent of cyclohexane and from about 10weight percent to about 35 weight percent of ethanol based on the totalweight of the first solvent mixture. In yet another embodiment, thefirst solvent includes a mixture of cyclohexane and ethanol in a ratiofrom about 70 weight percent cyclohexane and about 30 weight percent ofethanol based on the total weight of the first solvent mixture. In aparticular embodiment, the first solvent mixture comprises cyclohexaneand ethanol in a ratio from about 69 weight percent cyclohexane andabout 31 weight percent ethanol based on the total weight of the firstsolvent mixture.

In one embodiment, the first solvent is used in an amount correspondingto a weight ratio of first solvent mixture to the oil sand in a rangefrom about 3 to 1 to about 500 to 1. In another embodiment, the firstsolvent is used in an amount corresponding to a weight ratio of firstsolvent mixture to oil sand in a range from about 3 to 1 to about 50to 1. In yet another embodiment, the first solvent is used in an amountcorresponding to a weight ratio of first solvent mixture to oil sand ina range from about 3 to 1 to about 10 to 1.

In one embodiment, the contacting of the bitumen-containing oil sandwith the first solvent mixture is carried out for a period of timeranging from about 0.1 hour to about 24 hours. In another embodiment,the contacting of the bitumen-containing oil sand with the first solventmixture is carried out for a period of time ranging from about 3 hour toabout 15 hours. In one embodiment, the contacting of thebitumen-containing oil sand and the first solvent mixture is carried outat a temperature a range from about 25° C. to about 150° C. In anotherembodiment, the contacting of the bitumen-containing oil sand and thefirst solvent mixture is carried out at a temperature a range from about45° C. to about 120° C. In yet another embodiment, the contacting iscarried out at ambient temperature. In one embodiment, steam may becontacted with the extraction mixture.

The contacting of the bitumen-containing oil sand with the first solventprovides an extraction mixture. The extraction mixture includes a sandphase and an organic phase. The organic phase includes bitumen, ethanoland cyclohexane. The sand phase is separated from the organic phase. Theseparation of the sand phase from the organic phase may be carried outby techniques known to one skilled in the art. In one embodiment, theseparation of the sand phase and the oil phase may be carried out bygravity separation, i.e. a separation in which the product is subjectedto defined gravitational forces tending to separate the heavier sandfrom the lighter fluids. Examples of gravitational separation includebut are not limited to centrifugation, separation using a hydrocyclone,rotary filtration, simple filtration, and the like. In one embodiment, ahydrocyclone separation is employed which includes a plurality ofseparating stages. In certain embodiments, the sand phase obtainedfollowing contact with the first solvent mixture may be discarded asbitumen-free and solvent-free sand. In certain other embodiments, thesand phase may be separated from the extraction mixture and thereafterbe subjected to a second stage of extraction. In embodiments in whichthe oil sand is being treated in situ, the organic phase is removed fromthe spent sand phase by bringing the organic phase to the surface. Inembodiments involving in situ contacting of an oil sand with the firstsolvent mixture in a subsurface deposit, the first solvent mixture isintroduced into the subsurface deposit via at least one solvent inletconduit. The organic phase resulting from the contacting of the oil sandwith the first solvent mixture is thereafter removed via one or moreoutlet conduits. In one embodiment, the solvent inlet conduit alsoserves as the outlet conduit. In one embodiment, the solvent inletconduit delivers the first solvent to a subsurface oil sand depositwhile a plurality of outlet conduits arrayed radially about the edge ofthe subsurface oil sand deposit removes the resultant organic phasecomprising bitumen, cyclohexane and ethanol. In order to enhance therecovery of bitumen and solvent from the subsurface oil sand deposit,the first solvent mixture may be heated prior to or during contact withthe subsurface oil sand. In one embodiment, an inert gas or steam isused to enhance the removal of the organic phase from the subsurface oilsand deposit. In one embodiment, carbon dioxide is used to enhance theremoval of the organic phase from the subsurface oil sand deposit.

The organic phase separated from the sand phase may be treated in orderto separate and recover the cyclohexane and ethanol employed and torecover the bitumen component of the organic phase. In one embodiment,the organic phase is subjected to conditions under which the cyclohexaneand ethanol is removed from the organic phase by distillation. Invarious embodiments cyclohexane and ethanol are recovered as anazeotropic mixture comprising about 69% cyclohexane and about 31%ethanol. As is demonstrated herein, the use of an azeotropic mixture ofcyclohexane and ethanol provides a two-fold advantage in that theazeotropic mixture has a significantly lower boiling point (64.9° C.)than either of its constituents solvents cyclohexane (80.7° C.) andethanol (78° C.); and the extraction efficiency of cyclohexane-ethanolmixture with respect to bitumen recovery is superior to the puresolvents. The lower boiling point of the azeotropic mixture allowsrecovery of the first solvent mixture for reuse at a lower cost sinceless energy is required to effect its distillation. Thus, in oneembodiment, an azeotropic mixture of cyclohexane and ethanol isseparated from the organic phase. Those of ordinary skill in the artwill understand that a cyclohexane-ethanol mixture comprising 69%cyclohexane and 31% ethanol will have essentially the same compositionbefore and after distillation. When an azeotropic mixture (alsosometimes referred to as constant boiling mixture) is boiled theresulting vapor has the same ratio of the constituents cyclohexane andethanol, as the original mixture. The separating of the azeotropicmixture from the organic phase may be carried out by several methodsknown to one skilled in the art for example distillation, pressure swingdistillation, extractive distillation, chemical action separation,pervaporation, vapor permeation and the like. In one embodiment, theseparating the azeotropic mixture is carried out by distillation. In oneembodiment, the distillation is carried out at a pressure in a rangefrom about 0.1 atmospheres to about 5 atmospheres. In anotherembodiment, the separating the azeotropic mixture is carried out bydistillation at ambient pressure.

Recovery of bitumen from the organic phase may be carried out bytechniques known to one skilled in the art such as centrifugation,filtration and the like. In one embodiment, recovering of the bitumenfrom the organic phase includes reducing the temperature of the organicphase to effect precipitation of the bitumen from the organic phase andthereafter centrifuging of the mixture to further separate the bitumenfrom the organic phase. In one embodiment, the centrifugation of theorganic phase is carried out at a temperature in a range from aboutminus 40° C. to about 25° C. In another embodiment, the centrifugationof the organic phase is carried out at a temperature in a range fromabout minus 5° C. to about 20° C. In one embodiment, centrifugationresults in the formation of a lower bitumen layer and a supernatantliquid comprised chiefly of the first solvent mixture. The supernatantliquid may be decanted from the lower bitumen layer followingcentrifugation. In one embodiment, the recovery of the bitumen from theorganic phase is carried out prior to separating the azeotropic mixturefrom the organic phase. In another embodiment, the recovery of bitumenfrom the organic phase is carried out following separating theazeotropic mixture from the organic phase. In one embodiment, theextraction mixture is distilled to provide an “overhead” streamcomprising an azeotropic mixture of cyclohexane and ethanol and a“bottoms” stream of bitumen fluid. Such a process is amenable tocontinuous process steps operated at steady state.

In one embodiment of the present invention, the method further includesa drying step in which the organic phase is treated with a drying agentprior to separation of the azeotropic mixture comprising cyclohexane andethanol. Non-limiting examples of drying agents include anhydrous saltssuch as calcium chloride (CaCl₂), sodium sulfate (Na₂SO₄), calciumsulfate, magnesium sulfate (MgSO₄), and the like. In one embodiment, thesand phase after separation from the organic phase (spent sand) may beheated to remove any residual water and may be employed as a dryingagent in the drying step.

In some embodiments, the method includes a step of transporting theorganic phase to a second location remote from a first location at whichthe contacting is carried out. In one embodiment, the transportingcomprises transport by pipeline.

In various embodiments, the bitumen recovered may be transported andeventually upgraded into higher value products, for example syntheticoil. In one embodiment, the bitumen obtained after the recovery stepincludes less than about 1 parts per million (ppm) of impurities such asvanadium, nickel and sulfur compounds. In another embodiment, less thanabout 1 ppm of impurities such as vanadium compounds.

In another aspect of the present invention a method for recoveringbitumen from an oil sand that includes (a) contacting in-situ abitumen-containing oil sand in a subsurface deposit with a first solventmixture of cyclohexane and ethanol to provide an extraction mixture, asand phase and an organic phase, the first solvent mixture comprisingfrom about 95 to about 65 percent cyclohexane and from about 5 to about35 percent ethanol; (b) removing the organic phase comprising bitumen,cyclohexane and ethanol from the subsurface deposit; (c) separating anazeotropic mixture comprising cyclohexane and ethanol from the organicphase; and (d) recovering bitumen from the organic phase. In oneembodiment, the order of the steps may be interchangeable. In anotherembodiment, the order of steps (a)-(d) is first (a) then (b) then (c)then (d).

In another embodiment, the methods includes (a) contacting at ambienttemperature a bitumen-containing oil sand with a first solvent mixturecomprising about 69 cyclohexane and about 31 percent ethanol to providean extraction mixture comprising a sand phase and an organic phase; thefirst solvent mixture being used in an amount corresponding to a weightratio of first solvent mixture to oil sand in a range from about 3 to 1to about 500 to 1; (b) separating the sand phase from the organic phasecomprising bitumen, ethanol and cyclohexane; (c) separating anazeotropic mixture comprising cyclohexane and ethanol from the organicphase; and (d) recovering bitumen from the organic phase.

EXAMPLES Preparation of Oil Sand Models

Oil sand models were prepared as follows. Britesorb® D350EL silicaadsorbent (approximately 35 grams) was added to a blender, together withapproximately 100 g of Saudi heavy crude oil and 200 g of petroleumether. The resulting slurry was mixed for about five minutes at roomtemperature and was then poured into centrifuge tubes. Each tube wascentrifuged, and the resulting liquid fractions were decanted from theBritesorb® D350EL solids containing crude oil. The solids were driedunder vacuum at 80° C. for about two hours. The dried solids were thenanalyzed using a Thermogravimetric Analyzer (TGA). The percent weightloss between the initial onset of devolatization and/or decomposition atabout 200° C. to about 650° C. was interpreted to reflect the removal ofthe residual organic material (oil components) from the adsorbent. Theresults indicated that the model oil sands comprised about 34.2 wt. %oil components.

First solvent mixtures (wash solutions) comprising cyclohexane andethanol were prepared and are given in Table 1 together with data forthe recovery of oil components.

Oil sand models were contacted with first solvent mixture as follows.The oil sand model (0.5 g) was placed in a vial along with about 13 g ofthe particular wash solution being tested. The resulting slurry wasmixed for about five minutes on an auto-shaker at room temperature andpoured into a centrifuge tube. The tube was centrifuged and theresulting organic phase was decanted away from the model sand phase. Themodel sand phase was contacted two additional times with the samesolvent mixture as before. The model sand thus recovered was analyzed bythermogravimetric analysis (TGA) to determine an amount of oil remainingon the solid phase.

TGA was performed on 5-10 mg samples. The temperature was increased at arate of 10-20° C./minute to the desired final temperature in a rangefrom about 650° C. to about 700° C. During the analysis the sample wasexposed to a constant flow of air at 0.04 standard cubic feet per hour.As the temperature increased, oil components were volatilized and/ordecomposed and thereby removed from the solid adsorbent resulting in acorresponding weight loss. The weight loss corresponds precisely to theoil that was present within the adsorbent. By knowing the amount of oilinitial present in the model oil sand and the amount of oil remainingafter washing, an efficacy of the wash step can be quantified. Exemplaryresults are set forth in Table 1 below. The data show the unique abilityof solvent mixtures having compositions comprising from about 95 toabout 65 percent cyclohexane and from about 5 to about 35 percentethanol to effect the removal of the oil components from the oil sandmodel.

TABLE 1 Cyclohexane Ethanol Oil Removed Vanadium TGA (wt %) (wt %) (%)(ppm) % wt loss CEx. 1 100 0 41.4 — — CEx. 2 10 90 36.9 0.6 5.31 CEx. 30 100 35.4 <0.1   32.76  Ex. 1 90 10 99.3 — — Ex. 2 75 25 98.0 — — Ex. 350 50 71.8 — — Ex. 4 25 75 46.8 0.5 5.87

The foregoing examples are merely illustrative, serving to exemplifyonly some of the features of the invention. The appended claims areintended to claim the invention as broadly as it has been conceived andthe examples herein presented are illustrative of selected embodimentsfrom a manifold of all possible embodiments. Accordingly, it is theApplicants' intention that the appended claims are not to be limited bythe choice of examples utilized to illustrate features of the presentinvention. As used in the claims, the word “comprises” and itsgrammatical variants logically also subtend and include phrases ofvarying and differing extent such as for example, but not limitedthereto, “consisting essentially of” and “consisting of.” Wherenecessary, ranges have been supplied; those ranges are inclusive of allsub-ranges there between. It is to be expected that variations in theseranges will suggest themselves to a practitioner having ordinary skillin the art and where not already dedicated to the public, thosevariations should where possible be construed to be covered by theappended claims. It is also anticipated that advances in science andtechnology will make equivalents and substitutions possible that are notnow contemplated by reason of the imprecision of language and thesevariations should also be construed where possible to be covered by theappended claims.

1. A method for recovering bitumen from an oil sand, the methodcomprising: (a) contacting a bitumen-containing oil sand with a firstsolvent mixture of cyclohexane and ethanol to provide an extractionmixture comprising a sand phase and an organic phase, the first solventmixture comprising from about 95 to about 65 percent cyclohexane andfrom about 5 to about 35 percent ethanol; (b) separating the sand phasefrom the organic phase comprising bitumen, ethanol and cyclohexane; (c)separating an azeotropic mixture comprising cyclohexane and ethanol fromthe organic phase; and (d) recovering bitumen from the organic phase. 2.The method according to claim 1, further comprising a drying step inwhich the organic phase is treated with a drying agent.
 3. The methodaccording to claim 2, wherein the drying agent comprises anhydrousrecovered oil sand.
 4. The method according to claim 1, wherein thefirst solvent mixture is used in an amount corresponding to a weightratio of first solvent mixture to oil sand in a range from about 3 to 1to about 500 to
 1. 5. The method according to claim 1, wherein the firstsolvent mixture comprises about 70 percent cyclohexane and about 30percent ethanol.
 6. The method according to claim 1, wherein thecontacting is carried for a period of time ranging from about 0.1 hourto about 24 hours.
 7. The method according to claim 1, wherein thecontacting is carried out a temperature in a range from about 25° C. toabout 150° C.
 8. The method according to claim 1, wherein the recoveringbitumen from the organic phase is carried out prior to separating theazeotropic mixture from the organic phase.
 9. The method according toclaim 8, wherein the recovering bitumen comprises centrifugation of theorganic phase is carried out at a temperature in a range from aboutminus 40° C. to about 25° C.
 10. The method according to claim 1,wherein the recovering bitumen from the organic phase is carried outfollowing separating the azeotropic mixture from the organic phase. 11.The method according to claim 1, wherein the separating the azeotropicmixture is carried out by distillation at a pressure in a range fromabout 0.1 atmosphere to about 5 atmosphere.
 12. The method according toclaim 1, wherein the separating the azeotropic mixture is carried out bydistillation at ambient pressure.
 13. The method according to claim 1,further comprising a step of transporting the organic phase to a secondlocation remote from a first location at which the contacting is carriedout.
 14. The method according to claim 13, wherein the transportingcomprises transport by pipeline.
 15. A method for recovering bitumenfrom an oil sand, the method comprising: (a) contacting in-situ abitumen-containing oil sand in a subsurface deposit with a first solventmixture of cyclohexane and ethanol to provide an extraction mixture, asand phase and an organic phase, the first solvent mixture comprisingfrom about 95 to about 65 percent cyclohexane and from about 5 to about35 percent ethanol; (b) removing the organic phase comprising bitumen,cyclohexane and ethanol from the subsurface deposit; (c) separating anazeotropic mixture comprising cyclohexane and ethanol from the organicphase; and (d) recovering bitumen from the organic phase.
 16. The methodaccording to claim 15, wherein the order of steps (a)-(d) is first (a)then (b) then (c) then (d).
 17. The method according to claim 15,further comprising a drying step in which the organic phase is treatedwith a drying agent.
 18. The method according to claim 15, wherein thefirst solvent mixture is used in an amount corresponding to a weightratio of first solvent mixture to oil sand in a range from about 0.5 to1 to about 50 to
 1. 19. The method according to claim 15, wherein theseparating the azeotropic mixture is carried out by distillation at apressure in a range from about 0.1 atmosphere to about 5 atmosphere. 20.A method for recovering bitumen from an oil sand, the method comprising:(a) contacting at ambient temperature a bitumen-containing oil sand witha first solvent mixture comprising about 69 cyclohexane and about 31percent ethanol to provide an extraction mixture comprising a sand phaseand an organic phase; the first solvent mixture being used in an amountcorresponding to a weight ratio of first solvent mixture to oil sand ina range from about 3 to 1 to about 500 to 1; (b) separating the sandphase from the organic phase comprising bitumen, ethanol andcyclohexane; (c) separating an azeotropic mixture comprising cyclohexaneand ethanol from the organic phase; and (d) recovering bitumen from theorganic phase.